EFFECTIVENESS AND SAFETY OF BIOSURFACTANTS AS AGENTS OF OIL SPILL RESPONSE
| Autor: | Tim Reilly, Joe Eugene Lepo, M. Patricia Hancock, Katharine Roupp-Edwards, David E. Fritz, Candy L. Zuleger |
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| Rok vydání: | 1997 |
| Předmět: | |
| Zdroj: | International Oil Spill Conference Proceedings. 1997:687-696 |
| ISSN: | 2169-3358 2169-3366 |
| Popis: | Biosurfactants play an important role in facilitating the natural biodegradation of petroleum hydrocarbons. In order to characterize the biosurfactant-producing potential of environments at risk of anthropogenic oil contamination, we collected a number of distinct marine bacteria that emulsified crude oil from relatively pristine and from polluted areas. The bacteria belonged to diverse taxonomic groups and varied widely in oil-emulsifying capability, surface tension reduction of culture media, and hydrophobicity. We used laboratory assays that directly evaluated biosurfactant preparations from these and other strains for use as cleaning agents for oiled surfaces. The subjects of the study were the oil emulsification capabilities and the surface-active characteristics of the biosurfactants, which were compared to those of selected synthetic surfactants. We also examined the ability of different biosurfactants and synthetic surfactants to wash oil from porcelain tiles. To assess the efficacy of biosurfactants as enhancers of oil biodegradation, we applied preparations of biosurfactants along with our standard mix of hydrocarbon-degrading bacteria in either shake-flask experiments or in sandy-beach microcosms. In general, surfactants of either class (biosurfactants or synthetic surfactants) performed similarly in all of these experiments. Although some biosurfactants show merit as cleaning agents, the current production technology may not make their use cost-effective. Safety issues relating to biosurfactants were addressed by examining their toxicity and their biodegradability (and thus persistence in the environment) relative to selected synthetic surfactants. Standard toxicology bioassays were used: (1) the mysid, 7-day chronic estimator, and (2) the inland silverside 7-day chronic estimator. The biodegradability of biosurfactants and synthetic surfactants was compared by measuring the increased biochemical oxygen demand generated by the surfactants in raw seawater. Some biosurfactants were indeed highly biodegradable; however, we found no tight association of biodegradability to either class of surfactants. These results suggest that the environmental safety of surfactants is best evaluated on the basis of toxicity and degradability data for specific cases. |
| Databáze: | OpenAIRE |
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